To investigate the most effective way of cellulase utilization on paper making process and the systematic way of how to combine its components for better use, purified two major cellulase were applied to bleached kraft pulp at various dosage in the refining process and estimated the synergism effect of each components in the characteristics of papermaking fiber. freeness was not changed by $C_1$ Component dosage but strongly increased by Cx Component dosage. Drop in fiber viscosity, increase in WQV, fiber shortening and fine generation was strongly influenced by Cx Component, it seems to be that Cx Component works a hydrogenate that breaks hydrogen bonding in fiber and enhances pooling effect of fiber. $C_1$ Component was little influenced these characteristics of fiber but considered to help to make fiber surface smooth.